Piston



March 15, 1932. A. L, NELSON 13,384

PISTON Original Filed June 2, 192:5 2 Sheets-Sheet 1 l-Tgladorn,

March 15, 1932 A. L. NELSON Re. 18,384

PISTON Original Filed June 2, 1925 2 Sheets-Sheet 2 g] now 1* 01 AdolphLNeIson Reissuecl Mar. 15, 1932 PATENT OFFICE ADOLIPH L. NELSON, OFDETROIT, MICHIGAN, ASSIGNOB 'I'O BOHN ALUMINUM 8t BRASS CORPORATION, OFDETROIT, MICHIGAN PISTON Original No. 1,548,329, dated August 4, 1925,Serial No. 643,073, filed June 2, 1923. Application for reissue filedJuly 24, 1926. Serial No. 124,729.

\ My said invention relates to a piston for internal combustion enginesand the like and it is an object of the invention to separate the skirtfrom the head so that the skirt may be largely insulated from the actionof the heat on the head. In some instances also the skirt may be made ofdifferent material from the head, for example the head may lie made ofcast iron to minimize wear in the ring grooves while the skirt may be ofa relatively light and soft alloy. I

The main object of the invention is to provide 'a piston in which theskirt shall be relatively free from contraction and expansion being whencold in a condition of strain which is relieved when the skirt warms upbut due to such strain there is very little 'actualincrease in diameterduring the warming process. The advantages of such a construction inpreventing or decreasing the piston slap when the engine is cold and ininsuring the maintenance of a film of oil between the piston and the clinder at all times will be obvious to those ski led in the art.Subsidiary purposes are to provide eificient means for holding togetherthe separate head and skirt, to provide means insuring correct alinementof the head and the skirt, and to provide improved means for preventingaccess of oil to the cylinder above the piston.

Other purposes will appear upon consideration of the subjoineddescription.

Referring to the accompanying drawings which are made a part hereof andon which similar reference characters indicate similar parts,

Figure 1 is a central vertical section of one form of my invention,

Figure 2, a horizontal section of Figure 1 immediately above the upperstrut,

Figure 3, an inverted plan of Figure 1, Figure 4, a vertical centralsection of another form of my invention, on line 4--4 of Figure 5,

Figure 5, a section at right angles to Figure 4,

Figure 6, a detail of the upper strut in Figures 1 and 5, and

Figure 7 a detail of a modified strut,

In the drawings reference character 10 indicates the head of the pistonwhich is secured to the skirt 11 by means of bolts 12 en-' gagingthreaded openings in bosses 13 on the .head and fittingloosely inopenings through bosses 13 on the skirt. These bolts also extend throughopenings in the hollow piston pin 14 which is mounted in bearings on theextensions 13 and is held in fixed position by the bolts.

It will be understood that the lower ends of the bosses 13 .form thepiston pin bosses against which the piston pin bears, and the upperparts of the bosses 13 form necks extending above the piston pin bosses.

The skirt has an annular rim at 15 extending upwardly to surround thelower portion of the head and a disc strut 16, preferably made of asteel stamping, is located between the head and the adjacent part of theskirt, said strut fitting closely within the rim 15 ex- '70 cept at theparts nearest to the bolts 12 where the strut is relieved to a slightextent as at 17 to allow for cases where the cylinders go out of round.It will be seen that the strut acts as a rigid member to preventcontraction of the skirt in a direction transversely of the piston pinwhereas a slight contraction is permitted longitudinally of the pistonpin by the reliefs at 17, 17 The strut 16 has a central aperture adaptedto be engaged by a depending hollow boss 18 on the head of the piston.This boss fits closely within the opening and is of assistance inlocating the head in alinement with the skirt. The strut is alsoprovided at each side of a line passing through bolts 12 with groups ofopenings 18 arranged in semi-circles.

The disc strut 16 is set into the upper ends of the necks extendingabove the piston pin bosses, and can be said to be embedded in thenecks...

Beneath the piston pin is a bracing ring 19 apertured at diametricallyopposed points to accommodate the bolts 12 and having an ellipticalopening with its major axis transverse to the piston pin. This ringserves to limit the contraction of the lower part of the. skirt in thesame manner as strut 16 limits the contraction of the upper part and isrelieved at 19 in similar manner to strut 16.

The piston pin is flattened near its ends for secure engagement by thering 19 and washers 20 are placed between the heads of the bolts and thelower strut, these washers each having an arcuate surface at one side asindicated at 21 to bear against the inner surface of the skirt.

The skirt is slitted at intervals from above and below as shown at 22and 23, these slits serving a double purpose in that the upper slitsprovide a means for the excess oil to escape from the lowermost ringgroove through the slits to the interior of the piston, while both theupper and the lower slits act to take care of the expansion of thepiston. As the temperature of the piston rises the tongues betweenadjacent grooves spread laterally by a sort of sidewise crawling actionof their material to gradually fill the space normally occupied by theslits but because of the limitation imposed on contraction by the upperand lower struts there will be little or no radial expansion while thecontraction upon cooling will proceed in the reverse fashion by thegradual narrowing of the tongues but unaffected by any considerableradial movement in the skirt. It should be noted also that theseparation of the skirt from the head tends to insulate the skirt fromthe high temperature of the head, which effect is augmented by thematerial of the upper strut which should be selected partly. for itsrelative impermeability to heat as well as for thermal expansionproperties to limit expansion and contraction of the skirt to the degreedesired.

In the form of the invention shown in the figures heretofore describedthe upper strut has a series of holes at each side of a line passingthrough the bolts and a relief at each side at 17, the strut beingotherwise in the shape of a disk. In the modification of Figures 4 to 6I have shown the upper strut 24 as having its outer periphery in theform of a complete circle with openings at both sides of a diameterpassing through the bolts 25. This leaves a diametrical bridge at 26 forbracing the strut. A bridge 26' at right angles to bridge 26 is shown inFigure 7 and this will be found preferable in some cases, the wholemaking a cruciform bridge structure combining the parts 26 and 26 toprovide increased rigidity. The rigid brace formed by the bridge and theparts adjacent thereto is interrupted'only by the bolt holes 27 whichaccommodate the bolts 25 with a slight clear.- ance. For limiting theexpansion and contraction of the upper end of the skirt the strut has anannular groove on its underside adapted to engage an annular flange at28 on the skirt, the tongue 28 produced in forming the groove on thestrut engaging a groove in the skirt between the tongue 28 and the outerperiphery of the skirt. This is only one expedient for producing asecure engagement of the skirt and the strut and I may use other methodssuch as will be obvious to those skilled in the art. It will be obviousthat this tongue and groove connection between the disc strut and theend of the skirt can also be used in the structure shown in Figure 1.

The head 10 is secured to the skirt 11 by the bolts 25 having heads 30flush with the upper surface of the piston head and having knurledportions 31 with a press fit in the head. 1 The skirt is cutaway at bothsides beneath the piston bearing as shown at 33 and has slots 34extending from the upper end to a point below the lower part of thepiston pin, or otherwise expressed, to a point below the mid-length ofthe skirt. These slots and cut away portions provide space for thesidewise extension of the tongues formed thereby as above described andpermit the skirt to be held against radial extension or contraction bymeans of the upper strut 24 and a lower bracing ring 19. The ends of thering fit between raised parts 35 on the downwardly extending tongues ofthe skirt and the strut may be fastened to the parts 35 eitherpermanently or otherwise as desired.

'The bolts 25 fit in the holes in the skirt extensions 36 with aconsiderable clearance and passages 37 lead to such holes from theexterior of the piston at the upper end of the skirt, for the purpose ofleading excess oil to the interior of the piston.

' It will be seen that with my invention it is possible topreventdistortion of the piston in a very effective manner since theupper strut is either approximately in the form of Y a disk or in theform of a braced ring which cannot yield or go out of round, and whichby reason of its interlocking engagement with the upper end of the skirtaround the entire perimeter of the skirt effectively controls the sizeof the skirt along all diameters in the plane of the disc strut.

Various modifications of my device and the parts thereof will be obviousto those skilled in the art and therefore I do not limit myself to whatis shown in the drawings and described in the specification but only asindicated in the appended claims.

Having thus fully described my said invention, what I claim as new anddesire to secure by Letters Patent is:

1. A piston having a head, a skirt separa-. ble therefrom, and a strutbetween the head and the skirt said strutengaging the upper margin ofthe skirt to limit the expansion and contraction thereof, substantiallyas set forth.

2. A piston having a head, a skirt separable therefrom andlongitudinally slitted at its upper end, and a strut closely engagingthe inner surface of the skirt at its upper margin to preventcontraction thereof, substantially as set forth.

3. A piston having a head, a piston pin, a separable skirt having innerextensions forming bearings for the piston pin, bolts connecting thehead and the piston pin to the skirt said extensions having openingsfitting loosely about the bolts and one or more oil passages leading tosaid openings from the upper end of the skirt, substantially as setforth. I

4. A piston having a head, a skirt separable therefrom, an upwardlyextending rim on the skirt, a strut fitting closely within the rim andseparating the head and the skirt, and a boss on the head fitting Withinan opening of the strut to aline the head and the skirt, substantiallyas set forth.

5. A piston having a head, a skirt se ara- SlOIlS, an upwardly extendlngIJIH on the skirt, a piston pin, bolts extending upwardly through thepiston pin and said extensions on the skirt and engaging threadedopenings in the head, and a strut between the head and the skirt fittingclosely within the said rim and relieved at opposite sides adjacent saidbolts, substantially as set forth.

6. A piston having a head, a skirt separable therefrom havingdiametrically opposite inward extensions, bolts passing upward throughthe piston pin and said extensions into thehead for securing the partstogether said skirt having slits extending respectively from the upperand lower edges past the piston pin, and upper and lower struts to limitthe contraction of the skirt, substantially as set forth.

7 A piston having a head, a skirt separable therefrom havingdiametrically opposite inward extensions, a piston pin, bolts pass ingupward through the piston pin and said extensions into the head forsecuring the parts together said skirt having slits extendingrespectively from the upper and lower edges past the piston pin, andupper and lower struts bearing againstthe interior surface of the skirtto limit its contraction said lower strut being in the form of a ringresting against flattened end faces on the under side of the piston pin,substantially as set forth.

8. A piston having a head, a separable skirt having slits extending fromits upper and lower edges past the midlength'of the skirt, a strut atits upper end, and a strut below such midlength fitting closely againstthe inner periphery of the skirt to prevent radial contraction thereof,substantially as set forth.

9. A piston having a head, a separable skirt, a. strut separating thehead and the skirt, bolts in a plane passing through the piston pinconnecting the head and the skirt 55 said strut being rigid in adirection transverse 'sides adjacent to said bolts, substantially as bletherefrom having opposed inward e tento the piston pin and beingrelieved at the sides nearest the piston pin, substantially as setforth.

10. A piston having a head, a skirt separable therefrom havingdiametrically opposite inward extensions, bolts passing upward throughthe piston pin and said extensions into thehead for securing the partstogether said skirt having slits extending respectively from the upperand lower edges past the piston pin, and upper and lower struts to limitthe contraction of the skirt, each of said struts being relieved atopposite set forth. 0

11. In a piston, a unitary head, a skirt, a unitary piston pin flattenedat its lower side, bolts extending through the pin into the head, andmeans on said bolts engaging the fiat side of the pin to secure it inplace, substantially as set forth.

12. In a piston, a head, a skirt, a piston pin flattened at its lowerside, bolts extendin through the pin into the head, a flat-side annularstrut engaging the flat under side of the pin and the inside of theskirt, and means on the bolts engaging the strut to hold it in place,substantially as set forth.

13. In a piston, a head, a separate skirt having bosses at oppositesides with transverse apertures though the skirt, a piston pin in saidapertures said skirt being cut away from said apertures to its lower rimto provide piston pin bearings open at the lower side, and boltsextending through the pin and the head to hold the parts together,substantially as set forth.

14. In a piston, a hollow head having bosses at opposite sides, aseparate skirt having bosses in line with those on the head and havingtransverse apertures at their lower ends, a piston pin, and boltspassing through the pin and said bosses-to fix the pin in place,substantially as set forth.

15. In a piston, a unitary head, a unitary 11o piston pin flattened atits lower side, an independent skirt having bosses arranged between thepiston pin and the head, and bolts extending through the piston pin intothreaded engagement with the head, said bolts having heads engaging theflattened lower side of the piston pin, substantially as set forth.

16. A piston having a head, a skirt, a pin boss, and a strut between thehead and the pin boss said strut engaging the upper end of 0 the skirtto limit the expansion and contraction thereof, substantially as setforth.

17. A piston having a head, a skirt and a strut of relativelyinexpansible material engaging the skirt adjacent the head in a mannerto prevent expansion and contraction thereof, substantially as setforth.

18. A piston having a head, a skirt, and a circular strut said struthaving its outer periphery in engagement with the upper end of the skirtnear the head to prevent contraction thereof, substantially as setforth.

19. A piston having a head, a skirt, and a circular strut said struthaving its outer periphery formed for engagement with the upper end-ofthe skirt near the head in a manner to prevent expansion or contractionof said skirt, substantially as set forth. I

20. A piston comprising a head, a sk1rt, and a strut in the form of abraced ring in engagement circumferentially with the skirt to preventthe same from going out of round, substantially as set forth.

21. A piston having a head, a skirt, and a circular strut engaging theskirt adjacent the head said strut holding the skirt positively againstcontraction and expansion so as to provide a perfect circle with auniform clearance, substantially as set forth.

22. A piston comprising a head, a boss on the head, a. skirt, a rim onthe skirt, and a member between the head and skirt and coacting with theboss and rim to center the head and skirt relatively to each other.

23. In a piston, a head, a skirt separate therefrom, a strut between thehead and the skirt, the strut being provided with an opening and acentral project-ion on the head fitting the opening in the strut tocenter the head relatively to the remaining parts, substantially as setforth.

24. In a piston, a head, an independent skirt, a strut separating thehead and skirt, and means for centering the same comprising a rim on oneof the other parts fitting closely about the circumference of the strut,substantially as set forth.

25. In a piston, a head, an independent skirt, a strut interposedbetween said head and skirt, and bolts connecting the head and skirt thestrut being cut out to accommodate the bolts and bein relieved adjacentsuch cut-out portions, su stantially as and for the purpose set forth.

26. In a piston, a head, a skirt, a piston pin, and positive meansextending across the skirt and positively interlocked with the skirtabove the pin for controlling the diameter of the skirt alongdiametersperpendicw lar to each other.

27. A piston comprising a head, a skirt, piston pin bosses, necksextending upwardly from the bosses, and positive control means extendingacross the skirt above the pin for controlling the diameter of the skirtalong diameters perpendicular to each other, the control means beingembedded in the said necks.

28. A piston comprising a head, a skirt having pin bosses andcylinder-bearing portions separated from the head, the skirt beingformed with openings extending downwardly partway of the skirt and withopenings extending upwardly partway of the skirt, a relativelyinexpansible strut above the pin bosses and contacting with thecylinder-bearing portions to control the spacing of the cylinder-bearingportions, and a second relatively inexpansible strut below the pinbosses for controlling the spacing of the lower ends of thecylinder-bearing portions.

29. A pistoncomprising a head, a skirt and a platesepar'ating the headand the skirt, centering means formed on the skirt for coaction with theplate, and centering means formed on the head for coaction with theplate.

30. A piston comprising a head, a skirt having pin bosses andcylinder-bearing portions separated from the head, the skirt beingformed with openin s extending downwardly partway of the s irt and withopenings extending upwardly partway of the skirt, and a relatively inexansible strut above the pin bosses, the strut eing positivelyinterlocked with the cylinder-bearing portions to control expansion andcontraction thereof.

-31. A piston comprising a head, a skirt separate from the head, thehead and skirt being formed of light weight metal, a disc of materialhaving a lower rate of thermal expansion than that of the skirt, saiddisc separating the head and skirt to permit expansion of the headindependently of the skirt, and mean securing the skirt to the head.

32. A piston having a head, a skirt separable therefrom andlongitudinally slitted at its upper end, a strut closely engaging aninner surface of the skirt at its upper end to prevent contractionthereof said strut being in the form of a ring with a bridge extendingacross the same in line with the piston pin, substantially as set forth.

33. A piston having ahead, a skirt separable therefrom andlongitudinally slitted at its upper end, a strut closely engaging theinner surface of the skirt at its upper end to prevent contractionthereof said strut being in the form of a ring with a bridge extendingacross the same, substantially as set forth.

34. A piston having a head, a skirt separable therefrom andlongitudinally slitted at its upper end, a strut closely engaging theinner surface of the skirt at its upper end to prevent contractionthereof said strut being in the form of a ring with a bridgeextendingacross the same in line with the piston pin, substantially as set forth.

35. A piston having a head, a skirt separable therefrom andlongitudinally slitted at its upper end, a strut closely engaging theinner surface of the skirt at its upper end to prevent contractionthereof, said strut being in the form of a ring with a cruciform bridgehaving one member extending across the ring in line With the piston pinand another at right angles thereto, substantially as set forth.

In witness whereof, I have hereunto set my hand at Detroit, Michigan,this 22nd day of July, A. D. nineteen hundred and twentysix.

ADOLPH L. NELSON.

